. Definition & Pharmacological Class
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Generic Name:Â Eltrombopag olamine
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Therapeutic Category:Â Thrombopoietin receptor agonist (TPO-RA)
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Mechanism of Action:
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Binds to transmembrane domain of TPO receptor
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Stimulates JAK2/STAT5 pathway → megakaryocyte proliferation
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Increases platelet production in bone marrow
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2. Approved Indications
✅ FDA/EMA Approved Uses:
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Chronic Immune Thrombocytopenia (ITP)
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Adults and children ≥1 year
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Second-line after corticosteroids/IVIG failure
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Severe Aplastic Anemia (SAA)
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In combination with immunosuppressants
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Hepatitis C-Associated Thrombocytopenia
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Enables interferon-based antiviral therapy
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🚫 Important Limitations:
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Not for first-line ITP treatment
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Contraindicated in myelodysplastic syndromes
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Not approved for chemotherapy-induced thrombocytopenia
3. Pharmacokinetics
Parameter | Value | Clinical Significance |
---|---|---|
Bioavailability | 52% | Reduced with food |
Tmax | 2-6 hours | Take on empty stomach |
Half-life | 26-35 hours | Once daily dosing |
Protein binding | >99% | Caution in hepatic impairment |
Metabolism | Hepatic (CYP1A2/CYP2C8) | Drug interaction potential |
Excretion | Fecal (59%), renal (31%) | Dose adjustment not needed for renal impairment |
4. Dosage & Administration
Standard Dosing Guidelines:
Indication | Starting Dose | Titration | Maximum Dose |
---|---|---|---|
Adult ITP | 25 mg once daily | ↑ by 25 mg every 2 weeks | 75 mg/day |
Pediatric ITP (6-17 yrs) | 25 mg once daily | ↑ by 25 mg every 2 weeks | 75 mg/day |
Pediatric ITP (1-5 yrs) | 12.5 mg once daily | ↑ by 12.5 mg every 2 weeks | 75 mg/day |
SAA | 50 mg once daily* | Adjust based on response | 150 mg/day |
HCV Thrombocytopenia | 25 mg once daily | ↑ weekly as needed | 100 mg/day |
Administration Instructions:
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Take 1 hour before or 2 hours after meals
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Avoid concomitant:
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Dairy products (separate by ≥4 hours)
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Polyvalent cation-containing medications (antacids, iron supplements)
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Swallow tablet whole with water
5. Special Populations
Hepatic Impairment:
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Mild (Child-Pugh A): Reduce starting dose by 50%
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Moderate (Child-Pugh B): Reduce starting dose by 75%
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Severe (Child-Pugh C): Contraindicated
Ethnic Considerations:
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East Asian patients: Start at 50% reduced dose
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Consider genetic testing for UGT1A1 polymorphisms
Pediatric Use:
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Safety established down to 1 year old
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Use oral suspension for children <25 kg
6. Adverse Effects
Common (≥10%):
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Headache (22%)
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Nausea (13%)
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Fatigue (12%)
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Upper respiratory infection (11%)
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ALT elevation (10%)
Serious (Require Monitoring):
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Hepatotoxicity (2.5%)
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Thromboembolism (3%)
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Bone marrow fibrosis (long-term use)
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Cataract formation
7. Drug Interactions
Interacting Drug | Effect | Management |
---|---|---|
Polyvalent cations (Ca, Mg, Al, Fe) | ↓ Absorption | Separate by 4+ hours |
CYP1A2 inhibitors (fluvoxamine) | ↑ Eltrombopag levels | Monitor for toxicity |
CYP2C8 inducers (rifampin) | ↓ Efficacy | Consider dose increase |
Statins | ↑ Myopathy risk | Monitor CK levels |
8. Monitoring Requirements
Baseline:
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CBC with platelet count
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Liver function tests
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Renal function
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Ophthalmologic exam
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Bone marrow biopsy (if long-term use anticipated)
Ongoing:
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Weekly platelet counts until stable
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LFTs every 2 weeks ×2 months, then monthly
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Regular blood pressure monitoring
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Annual:
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Eye exams
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Bone marrow evaluation (if chronic use)
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9. Storage & Handling
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Store at 20-25°C (68-77°F)
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Keep in original packaging (moisture sensitive)
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Protect from light
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Shelf life: 24 months unopened
10. Cost & Availability
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Brand Name Cost:Â ~$4,500/month
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Generic Availability:Â Limited (check local formularies)
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Patient Assistance Programs:Â Available through manufacturer
11. Clinical Pearls
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Dose Adjustment Triggers:
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Platelets >150,000/μL: Reduce dose
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Platelets >400,000/μL: Hold dose
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No response after 4 weeks: Discontinue
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Transitioning Between Formulations:
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25 mg tablet ≈ 24 mg oral suspension
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Monitor platelets closely when switching
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Overdose Management:
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Symptomatic treatment
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Monitor for thrombocytosis
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Consider plateletpheresis if platelets >1,000,000/μL
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Discontinuation Protocol:
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Taper gradually to avoid thrombocytopenia rebound
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Monitor platelets for ≥4 weeks post-discontinuation
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